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kanisama

Audio/video issues

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Hi all, I recently had a system repaired from "no AV" to "almost working" by having the quartz timing crystal replaced.  Now, I get AV but the signal has some issues - sometimes it has lines briefly across the screen, or sometimes the audio pops for a second.  Almost like there is a small amount of interference in the signal.  But there's something else slightly worse - during the games included in the system, there are many flickering black lines across the screen as well as input issues.  Weirdly, I can only play these games if I use one hand to hold down one of the buttons in the top row of the calculator pad on the system.  If I do this, the AV issues and input issues disappear and I can play normally.  Cartridge games do not seem to have this problem.

 

I have tried taking out the RF box and cleaning the contacts (both the port and connection to the board) with alcohol as best I could without opening the box itself, but this has only helped a little, if at all.  I'm wondering if there's anything I need to replace, short of just trying everything.  New RF cable, new RF box?  Something else completely?  Any help is appreciated.  For reference, the system is a Bally Computer System.  I can provide more model numbers or a video if that would help diagnose.

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18 hours ago, kanisama said:

I'm wondering if there's anything I need to replace, short of just trying everything.  New RF cable, new RF box?  Something else completely?  Any help is appreciated.

 

First off, it's great to hear that you fixed your Bally's issue by replacing the crystal.  I haven't heard of that as an issue until now.  As for your sometimes-interference, this sounds like a loose connection of some kind, but it may be hard to track down.

 

I re-posted your plea for help with your Bally's interference to Groups.io, which is sometimes more active than the AtariAge forums:

 

https://groups.io/g/ballyalley/topic/bally_console_with/69251830?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,69251830

 

You'll have to be a member of groups.io to read the post I made there, but I did ask anyone who could help to post any suggestions for you here on AtariAge.

 

Good luck getting your system running perfectly!

 

Adam

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The problem seem to be in either the on board ROM or the Custom I/O chip. There is a SLIGHT chanch that it could be one of the other2 customs chips.

Ken Lill

P.S. There is even a slighter chance that any of the following capacitors is bad: C24, C31, C38 or C45. R31 may be bad. Also one of these diodes: CR9. CR14, CR19 or CR24. I have listed the type of parts on this P>S> in the order I think they may go bad and cause this problem.

Edited by kenzre
left out info

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https://ballyalley.com/documentation/misc_hardware_docs/Bally/full_size/bally_service_manual.pdf

There's a direct link for ballyalley to the parts kenzre is talking about.  Parts list starts on page 19, and parts layout starts on page 24. 

 

I'm very curious to know what you find if you are able to fix this.  I have a unit that does pretty much the same thing, and I'm thinking of making it my bench/tester unit until I can figure out what's causing it.  I have too much other garbage going on to dig into it at the moment, but I've been wondering for months what's causing the issue.  If I can get into mine and figure it out, I'll let you know, and I'd appreciate the same.  I am going to try putting in new capacitors and seeing if that would do the trick, but I'm WAY more hopeful than I am optimistic that will fix it.

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Thank you guys very much for the info.  I will make sure to post back here if/when I get it figured out.  It may take a while as I lack some of the skills to implement these fixes, and in the end it might be "good enough", but anything I find out will make its way back here.

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